. >> reporter: this old copy of the declaration of independence cost $2.48 plus tax at a thrift store. turned out to be uber old and sold at auction for nearly half a million. >> and look for something chinese? >> yes. >> chinese is one of the hardest fields to appraise. >> reporter: even experts don't always know the chinese gems from the junk. upping the odds of a masterpiece with a $3 price tag. >> always buy what appeals to you and you will never go wrong. >> reporter: back to my little cup. >> certainly before 1872. >> reporter: really? it's old, it's chinese, and i like it, but -- >> the reality, you'll probably get no more than five to $10 for it. >> reporter: proving luck really is the key. so i'm not quitting my job. see you tomorrow. nick watt, abc news, los angeles. >> see you tomorrow, which means it's lucky for us, nick. we thank you for watching. hope to see you tomorrow as well. we're always there at abcnews.com. and "nightline" at its new time tonight, 12:35 a.m. eastern. again, right back here again tomorrow night. goodnight. see you then. >>> tonight what you can get